Ž . Applied Surface Science 162–163 2000 492–498 www.elsevier.nlrlocaterapsusc Influence of oxidation conditions on the properties of indium oxide thin films Mihaela Girtan ) , G.I. Rusu, G.G. Rusu, S. Gurlui Solid State Department, Faculty of Physics, Al.I. Cuza, UniÕersity of Iasi, Bd. Copou nr. 11, Ias ¸i R-6600, Romania Abstract Ž . Indium oxide In O thin films have been prepared by thermal evaporation of indium in vacuum on a glass substrate at 2 3 room temperature, followed by thermal oxidation in air. It was experimentally established that the heating velocity during the oxidation process has a strong influence on the electrical and optical properties of films as prepared. The temperature was increased from room temperature to 4508C, with velocities ranging between 0.18Crs and 0.58Crs. In O thin films as 2 3 obtained have been examined for optical transparency function on wavelength. The calculated values of optical band gap range between 2.99 and 3.31 eV. Electrical conductivity measurements have also been carried out on the above oxide thin films as a function of temperature. Both the electrical and optical studies showed that In O thin films with higher 2 3 transparency and electrical conductivity are obtained at higher oxidation velocities. Also, the experimental results show linear dependences of transmission coefficient on the oxidation velocity. q 2000 Elsevier Science B.V. All rights reserved. Keywords: Semiconductor; Indium oxide; Thermal oxidation velocity; Optical transmission; Electrical conduction 1. Introduction Ž . Indium oxide In O is a wide band gap n-type 2 3 oxide semiconductor. It has a low resistivity, which is an unusual property for a wide band gap material, compared with conventional semiconductors doped with impurities. The good conductivity of this film is a result of very high doping due to incomplete oxidation. In O thin films are characterized by high 2 3 ) Corresponding author. Tel.: q 40-32-201-169; fax: q 40-32- 213-330. Ž . E-mail address: girtan@uaic.ro M. Girtan . transparency in the visible region of the spectrum and high reflectance in the infrared region. The production and properties of transparent con- Ž . ducting oxide TCO thin films, such as In O , SnO 2 3 2 Ž . and indium tin oxide ITO , have been extensively studied since the films find use in a variety of applications; among the most important are solar w x cells, flat panel displays and diffusion barriers 1–4 . Several methods for their formation have been pro- posed and evaluated, including chemical vapor depo- sition sputtering, reactive evaporation, thermal oxida- w x tion, spraying, etc. 5–10 . In the present study, we have investigated the electrical and optical properties of In O thin films prepared by thermal oxidation of 2 3 indium films vacuum-deposited on glass substrates. 0169-4332r00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž . PII: S0169-4332 00 00238-5